Avaliação do efeito do extrato, frações e alcaloides piperidínicos obtidos das flores de Senna spectabilis (DC.) sobre Schistosoma mansoni

Abstract

Schistosomiasis is a chronic parasitic disease caused by parasites of the genus Schistosoma and presents a significant social and economic impact. Currently, praziquantel (PZQ) is the drug used for the treatment of the disease, indicated by the World Health Organization. However, the dependence on a single drug is concerning, since with constant reinfections and retreatment the emergence of resistant strains can occur. Therefore, the search for new compounds with schistosomicidal activity is essential. The genus Senna is the subject of many studies due to the recognition of its great biological diversity and pharmacological properties. In the present study, in vitro schistosomicidal activity was evaluated of the ethanolic extract, fractions from the extract and majoritarian alkaloids obtained from Senna spectabilis flowers. From the last two compounds, the cercaricidal activity and its effect in interaction with PZQ were also evaluated. The adult worms of S. mansoni were exposed to different concentrations of ethanolic extract (EEt), ethyl acetate (FAE) and dichloromethane (FDm) fractions, and mixtures of compounds cassina/espectalina for the assessment of parasites viability and calculation of the inhibitory concentration of 50%. The excretory activity and tegument lesions of adult worms of S. mansoni exposed to the mixture of alkaloids cassina/espectalina were evaluated through staining with fluorescent probes. Cell viability was assessed using human peripheral blood mononuclear cells (PBMC) by MTT reduction assay. The (EEt) and (FAE) of S. spectabilis, in high concentrations, cause decrease in oviposition, excretory system shutdown and tegument lesions. FDm fraction has significant activity when compared to the control, as this activity is result of higher concentration of alkaloids in this fraction. The mixture (cassina/espectalina) caused complete paralysis of adult worms of S. mansoni, in addition to inhibit the excretory activity and lead to considerable tegument lesions in the concentration of 50.0µg/mL. Regarding cercaricidal activity, the above-mentioned alkaloids caused paralysis and tail loss starting at a concentration of 50.0 µg/mL, and relevant results were obtained in the synergism with PZQ. The alkaloids mixture also showed low DL50 value 34.7µg/mL; and presented potential moderate cytotoxic CC50 132.1µg/mL. These results are promising regarding the schistosomicidal activity, therefore require further study.